1. Field of the Invention
The present invention relates to a technology for communicating between a plurality of communication terminals and, more particularly, to a technology of efficiently executing an application in a wireless network.
2. Description of the Related Art
With the realization of miniaturization and lightweight of information terminals, it has become common for people to carry an information terminal. Wireless communication environment in which a plurality of users can enjoy an application such as a game together using infrastructure such as base stations and access points has become a reality in recent years. Study has also been undertaken on the construction of wireless ad hoc network for on-demand communication. In an ad hoc network, base stations and access points are not necessary. It is therefore easy to build a wireless network even in places where no such infrastructure exists. In an ad hoc network, a plurality of users can enjoy a game together as they join each other, bringing their own portable game devices and communicating wirelessly.
An infrastructure network and an ad hoc network are built using technologies such as IEEE802.11 or Bluetooth. A wireless communication environment assumed conventionally is such that several terminals are brought together so that communication is achieved between the terminals. In an infrastructure network or an ad hoc network, however, a situation could occur in which as many as 10-100 terminals are brought together in the same environment.
In a wireless network using IEEE802.11, a Basic Service Set (BSS) is prescribed as a basic unit of group comprising terminals communicating with each other. BSS refers to a set which is a group of mutually communicating terminals. Terminals belonging to the same BSS can communicate with each other. A BSS is identified by a 48-bit identifier known as Basic Service Set ID (BSSID). A unique value in the environment is assigned to a BSSID. There is also available a Service Set ID (SSID) comprised of a character string of 0-32 bytes to discriminate between BSSs. SSID may be arbitrary set up. The same SSID may be assigned to a plurality of BSSs. A BSS is formed by a terminal or an access point transmitting a reference packet called beacon. The range reached by the beacon defines a spatial range of the BSS. A plurality of BSSs may be located in the same physical space.
When using a wireless network using IEEE802.11, a terminal is required to belong to one of the BSSs available. For this purpose, the terminal searches for (scans) BSSs located in its neighborhood. When participating in an existing group, the terminal may specify an SSID in case it has the knowledge of the SSID of a group in which participation is sought. In contrast, if the SSID is not known, the terminal scans all BSSs in its neighborhood and specifies an SSID selected from the SSIDs identified as a result of the search.
In a wireless LAN system of the infrastructure mode using access points, an access point transmits a beacon so as to form a BSS. In a majority of cases, an access point is connected to the Internet or a private network such as an enterprise network. Normally, a manager of such a network determines an SSID and sets up an access point accordingly. Uses of the network are informed of the SSID from the network manager and are involved in wireless communication accordingly.
In a wireless LAN system of an ad hoc mode not using access points, a network manager is not available. Therefore, users of the network have to determine an SSID themselves for connection. In this case, mutual connection is impossible unless the terminals select the same SSID. Therefore, it is necessary for the users to agree upon an SSID prior to communication. Since an SSID can be arbitrarily set up, connection may be established to an undesired wireless network if the same SSID is used in different groups. Thus, the setting of an SSID in an ad hoc network is a complicated process for users to perform. Further, stability in communication is difficult to achieve in an environment in which a large number of wireless networks are built in the same environment.